Both the Third Generation Partnership Project (3GPP) and 3GPP2, in order to keep the technology competitive for a longer time period, are considering long term evolution. Accordingly, evolution of radio interfaces and network architecture is necessary to support this goal.
Currently, orthogonal frequency division multiple access (OFDMA) is being considered for the downlink of evolved universal terrestrial radio access (E-UTRA). In the current state of the art, when a user equipment (UE) powers on in the E-UTRA system having an OFDMA based downlink, it synchronizes frequency, downlink frame timing and the Fast Fourier Transform (FFT) symbol timing with the best cell. In addition, the UE identifies the cell ID. This collective process may be referred to as the “cell search.”
The synchronization channel and cell search process for OFDMA-based downlink are currently being studied in E-UTRA. It would be desirable to define a synchronization channel that is a common for all cells in the system. In one regard, it has been determined that that downlink synchronization channel (SCH) is transmitted using 1.25 MHz or 5 MHz bandwidth regardless of the entire bandwidth of the system. In this way, the same SCH is mapped to the central part of transmission bandwidth.
Given the differences between universal mobile telecommunications system (UMTS) UTRA and evolved UTRA, it would be desirable to provide a new secondary SCH (S-SCH) for evolved UTRA.